Production Of SO2 Research Articles

Integrated lipid production, CO2 fixation, and removal of SO2 and NO from simulated flue gas by oleaginous Chlorella pyrenoidosa.

CO2, SO2, and NO are the main components of flue gas and can cause serious environmental issues. Utilization of these compounds in oleaginous microalgae cultivation not only could reduce air pollution but could also produce feedstock for biodiesel production. However, the continuous input of SO2 and NO inhibits microalgal growth. In this study, the toxicity of simulated flue gas (15% CO2, 0.03% SO2, and 0.03% NO, balanced with N2) was reduced through automatic pH feedback control. Integrated lipid production and CO2 fixation with the removal of SO2 and NO was achieved. Using this technique, a lipid content of 38.0% DW was achieved in Chlorella pyrenoidosa XQ-20044. The lipid composition and fatty acid profile indicated that lipid production by C. pyrenoidosa XQ-20044 cultured with flue gas is suitable as a biodiesel feedstock; 81.2% of the total lipids were neutral lipids and 99.5% of the total fatty acids were C16 and C18. The ratio of saturated fatty acids to monounsaturated fatty acids in the microalgal lipid content was 74.5%. In addition, CO2, SO2, and NO from the simulated flue gas were fixed and converted to biomass and lipids with a removal efficiency of 95.9%, 100%, and 84.2%, respectively. Furthermore, the utilization efficiencies of CO2, SO2, and NO were equal to or very close to their removal efficiencies. These results provide a novel strategy for combining biodiesel production with biofixation of flue gas.

Solar hydrogen production using direct coupling of SO2 depolarized electrolyser to a solar photovoltaic system

To obtain clean hydrogen production from a renewable energy source, direct coupling of photovoltaic and SO2 depolarized electrolysis (SDE) is one of the most promising alternative options. Both incident solar radiation variability and operating SDE parameters can affect the performance of such system. However, a big challenge is to have an efficient relative sizing. In fact, relative sizing is always a key issue when coupling renewable electric sources to SDE electrolysers. The aim is to determine the operation conditions and the optimal size of the direct coupling of a photovoltaic array to a SDE that ensure maximum hydrogen production while minimizing the energy consumption. In this study, a detailed two part-modeling approach has been used to estimate a system relative sizing for hydrogen production in a desired location. First, a simple model based on the extraction of the maximum power delivered by the photovoltaic array as function of temperature conditions and solar irradiation is developed. The model results are validated with experimental data of commercial PV module Second and in order to predict the maximum hydrogen production of SO2 depolarized electrolysis as a function of the consumed power, the SDE polarization curve is determined using a model and validated by experimental data. For the site of Bouzareah (Algiers), the results indicate that, for the case of global solar radiation on horizontal surface, the optimal combination of the integrated system is of one stack of 14 cells mounted in series and 17 stacks of 14 cells connected in parallel. In this case the global annual loss is 14.11%. For the same site but in the case of the global solar radiation on tilted surface, though the best sizing is still the same combination of series/parallel cells, the global annual loss is 20.80%.

Determination of the transport routes of and the areas potentially affected by SO2 emanating from Khatoonabad Copper Smelter (KCS), Kerman province, Iran using HYSPLIT

Forward trajectories were calculated from 1 January 2005 to 30 December 2016 using HYSPLIT to determine seasonal variation of potential transport pathways of SO2 emanating from KCS and identify the most affected areas around it. Then, the air parcels of each forward trajectory were divided into three height levels: 0–100 m above the ground level (agl.), 100–1000 m agl. 1000–5000 m agl. Finally, Kernel density analysis was conducted through a GIS tool to plot forward air parcels density maps. These show that the potential transport routes vary seasonally as well as the potential distances. Transport distance is approximately two times higher in winter than in summer, and it is equal for spring and autumn. The forward air parcels trajectory calculations have shown that there are two main corridors for transporting SO2 emanating from KCS towards to the northeast and south direction of this copper smelter. SO2 mainly transport through both corridors in spring and autumn and affect Rafsanjan and Sirjan cities and Bahram-e Goor Protected Area (PA). In summer, air parcels convey SO2 mainly in south direction and influence Bahram-e Goor PA and Darab city. The northeastern corridor is highly active in winter, and within this route, Rafsanjan City and Chah Koume PA are potentially affected. Shahr-e Babak is placed near the source and is highly affected in all seasons except winter. The wide spatial extent of SO2 transport besides KCS’ long-term production of SO2 imply the significant negative impact of this copper smelter on human health and the environment.

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ПРОЦЕССОВ РЕКТИФИКАЦИИ БЕНЗОЛА И ВЛАГОУДАЛЕНИЯ ИЗ КУБОВОГО ОСТАТКА ДЛЯ ЕГО УТИЛИЗАЦИИ

When rectifying benzene, bottoms residue is formed, which is a composition of non-hydrated aromatic hydrocarbons. Its utilization is possible by using it in the printing industry for the production of solvents, industrial oils, SO2 and sulfuric acid, soot, carbon black. In addition, alkaline waters from benzene rectification are used to remove carbonate deposits from oil wells, as well as additives to road tar, etc. For convenience of storage, transportation and use, it is advisable to obtain alkaline waters in dry form. Due to the fact that alkaline waters are a surfactant, a variant of drying by means of coating the working surface by foam extruders with a volumetric IR energy supply is chosen for it. As a result of the carried out experimental studies, their analysis and mathematical processing, there have been obtained approximating equations of dependence of specific productivity of the process on influencing factors, as well as equations of dependence of the IR drying rate of alkaline waters on their moisture content. On the basis of empirical study of kinetic regularities of radiation drying of alkaline waters, a method is chosen and a rational regime for the process is justified; mathematically adequate dependences of the specific productivity and the rate of moisture removal from the influencing factors are obtained. Compared with spray drying, specific yield of the finished product is 3 times higher with IR drying and amounted to 24 kg/(m3 ∙ h)) with 20% reduction in energy costs. It has been stated that for organizing a rational method of drying alkaline waters from benzene rectification, it is expedient to maintain the following regime parameters of dehydration: С н = 0.5 kg/kg, Ер = 3.23 kW/m 2, d н = 4 mm

Effect of grape juice composition and nutrient supplementation on the production of sulfur dioxide and carboxylic compounds bySaccharomyces cerevisiae

Background and Aims For health‐related reasons, it is crucial to reduce or even eliminate the use of SO2 in wines. The aim of this work was to assess and compare the influence of different Saccharomyces cerevisiae strains, and composition and nutritive supplementation of musts, on the production of SO2 and carboxylic compounds during alcoholic fermentation. Methods and Results Tempranillo and Albarino musts, supplemented with nitrogen and nutrients, from the 2013 to 2015 vintages, were fermented with several S. cerevisiae strains. The SO2 concentration in wines was more influenced by the yeast strain than by the addition of nitrogen. The addition of diammonium phosphate in combination with thiamine reduced the concentration of α‐ketoglutarate. The SO2 production by high and low sulfite‐forming strains depended on the composition of the musts. High sugar concentration and low nitrogen concentration in musts favoured the production of SO2 in wines. Conclusions The opportunity to produce SO2‐free wines from Albarino and Tempranillo by commercial and indigenous S. cerevisiae yeast strains has been shown. The composition of musts can greatly influence the SO2 produced. Moreover, the addition of nitrogen and nutrients can also influence the concentration of carboxylic compounds of wines. Significance of the Study This work contributes to an improved understanding of how to produce SO2‐free wines and may assist decision‐making during winemaking to obtain wines with a low potential to generate allergic reactions in consumers.

Production of SO2 Binding Compounds and SO2 by Saccharomyces during Alcoholic Fermentation and the Impact on Malolactic Fermentation

The objective of this study was to investigate the production of SO2 and SO2 binding compounds by wine yeast and the impact of the production of these compounds on the MLF at various time points during alcoholic fermentation. Fermentations were observed for a number of commercial wine yeasts in a synthetic grape juice and Pinot gris juice and SO2, acetaldehyde, pyruvic acid and α-ketoglutarate. Measurements were taken at multiple time points during the fermentation. Samples were taken from the fermentations at weekly intervals, sterile filtered, and inoculated with O. oeni strain VFO to induce MLF. Significant differences between the amount of SO2, acetaldehyde and pyruvic acid produced by the various yeast strains were noted. Some yeast strains such as FX10, CK S102, F15 and M69, produced significantly higher SO2 concentrations than other yeast strains and MLF was inhibited in these wines. Insignificant free SO2 was measured, indicating that bound SO2 rather than free SO2 was responsible for inhibition. At almost all time points of the alcoholic fermentation, acetaldehyde bound SO2 was determined to be the dominant species of bound SO2 present, suggesting that MLF inhibition by bound SO2 was due to acetaldehyde bound SO2.

FORMATION OF S-BEARING SPECIES BY VUV/EUV IRRADIATION OF H2S-CONTAINING ICE MIXTURES: PHOTON ENERGY AND CARBON SOURCE EFFECTS

Carbonyl sulfide (OCS) is a key molecule in astrobiology that acts as a catalyst in peptide synthesis by coupling amino acids. Experimental studies suggest that hydrogen sulfide (H2S), a precursor of OCS, could be present in astrophysical environments. In the present study, we used a microwave-discharge hydrogen-flow lamp, simulating the interstellar UV field, and a monochromatic synchrotron light beam to irradiate CO:H2S and CO2:H2S ice mixtures at 14 K with vacuum ultraviolet (VUV) or extreme ultraviolet (EUV) photons in order to study the effect of the photon energy and carbon source on the formation mechanisms and production yields of S-containing products (CS2, OCS, SO2, etc.). Results show that (1) the photo-induced OCS production efficiency in CO:H2S ice mixtures is higher than that of CO2:H2S ice mixtures; (2) a lower concentration of H2S enhances the production efficiency of OCS in both ice mixtures; and (3) the formation pathways of CS2 differ significantly upon VUV and EUV irradiations. Furthermore, CS2 was produced only after VUV photoprocessing of CO:H2S ices, while the VUV-induced production of SO2 occurred only in CO2:H2S ice mixtures. More generally, the production yields of OCS, H2S2, and CS2 were studied as a function of the irradiation photon energy. Heavy S-bearing compounds were also observed using mass spectrometry during the warm-up of VUV/EUV-irradiated CO:H2S ice mixtures. The presence of S-polymers in dust grains may account for the missing sulfur in dense clouds and circumstellar environments.

Decomposition of ammonia and hydrogen sulfide in simulated sludge drying waste gas by a novel non-thermal plasma

To efficiently clean NH3 and H2S contained in municipal sewage sludge drying waste gas, experiments were conducted with a novel gliding arc discharge plasma reactor. Important parameters including applied voltage and gas velocity which can strongly influence the removal efficiency, energy cost and by-products yields were investigated. Maximum removal efficiencies were all obtained at the applied voltage of 11kV and gas velocity of 4.72ms−1. When NH3 and H2S were treated together, the total energy cost decreased by 38%. NO and SO2 were observed as main decomposition by-products, and the presence of NH3 may inhibit the production of SO2 whose yield decreased from 223.8 to 27.8mgm−3. Tests performed on lab scale reactor showed that gliding arc discharge is efficient in decreasing the NH3 and H2S concentrations, and experiments will also be conducted on a larger scale reactor in the future.

직접 황 회수 공정으로 유입되는 재생가스에 함유된 미량산소의 촉매활성저하 원인 규명

In order to regenerate the sulfidated desulfurization sorbent, oxygen is used as the oxidant agent on the regeneration process. The small amount of oxygen un-reacted in regeneration process is flowed into direct sulfur recovery process. However, the reactivity for SO2 reduction can be deteriorated with the un-reacted oxygen by various reasons. In this study, the deactivation effects of un-reacted oxygen contained in the off-gas of regeneration process flowed into direct sulfur recovery process of hot gas desulfurization system were investigated. Sn-Zr based catalysts were used as the catalyst for SO2 reduction. The contents of SO2 and O2 contained in the regenerator off-gas used as the reactants were fixed to 5.0 vol% and 4.0 vol%, respectively. The catalytic activity tests with a Sn-Zr based catalyst were for SO2 reduction performed at 300-450 ℃ and 1-20 atm. The un-reacted oxygen oxidized the elemental sulfur produced by SO2 catalytic reduction and the conversion of SO2 was reduced due to the production of SO2. However, the temperature for the oxidation of elemental sulfur increased with increasing pressure in the catalytic reactor. Therefore, it was concluded that the decrease of reactivity at high pressure is occurred by catalytic deactivation, which is the re-oxidation of lattice oxygen vacancy in Sn-Zr based catalyst with the un-reacted oxygen on the catalysis by redox mechanism. Meanwhile the un-reacted oxygen oxidized CO supplied as the reducing agent and the temperature in the catalyst packed bed also increased due to the combustion of CO. It was concluded that the rapidly increasing temperature in the packed bed can induce the catalytic deactivation such as the sintering of active components.

An airborne assessment of atmospheric particulate emissions from the processing of Athabasca oil sands

Abstract. During the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign, two NASA research aircraft, a DC-8 and a P-3B, were outfitted with extensive trace gas (the DC-8) and aerosol (both aircraft) instrumentation. Each aircraft spent about a half hour sampling air around the oil sands mining and upgrading facilities near Ft. McMurray, Alberta, Canada. The DC-8 circled the area, while the P-3B flew directly over the upgrading plants, sampling close to the exhaust stacks, then headed downwind to monitor the aerosol as it aged. At short range, the plume from the oil sands is a complex mosaic of freshly nucleated ultrafine particles from a SO2- and NO2-rich plume, soot and possibly fly ash from industrial processes, and dust from dirt roads and mining operations. Shortly downwind, organic aerosol appears in quantities that rival SO4, either as volatile organic vapors condense or as they react with the H2SO4. The DC-8 pattern allowed us to integrate total flux from the oil sands facilities within about a factor of 2 uncertainty that spanned values consistent with 2008 estimates from reported SO2 and NO2 emissions, though there is no reason to expect one flyby to represent average conditions. In contrast, CO fluxes exceeded reported regional emissions, due either to variability in production or sources missing from the emissions inventory. The conversion rate of SO2 to aerosol SO4 of ~6% per hour is consistent with earlier reports, though OH concentrations are insufficient to accomplish this. Other oxidation pathways must be active. Altogether, organic aerosol and black carbon emissions from the oil sands operations are small compared with annual forest fire emissions in Canada. The oil sands do contribute significant sulfate and exceed fire production of SO2 by an order of magnitude.

Comparison of Radiation Resistant among Polysulfones Prepared from Several Aromatic Diol and 4,4’-Dichlorodiphenyl Sulfone

An aromatic polysulfone consists of 4,4’-diol aromatic compound and 4,4’-dichlorodiphenyl sulfone. As 4,4’-diol aromatic compounds, there exists bisphenol A, p-dihydroxy benzene, 4,4’-diphenol methane and p,p’-diphenol (bisphenol) and they were compared to study which compound would indicate the most resistant to gamma-ray exposure. Sulfur dioxide (SO2) from 4,4’-dichlorodiphenyl sulfone was used as an indicator for evaluation. The use of bisphenol in the preparation of polysulfone indicated the most resistant to the gamma-ray irradiation exposure and least production of SO2 among aromatic diol compounds tested. This indicated polysulfone free from bisphenol A is producible. The production of SO2 from bisphenol-based polysulfone was around 43% of bisphenol A based polysulfone. The rate of decrease of tensile strength correlated well with the order of radiation resistance. The fracture toughness of bisphenol A based polysulfone decreased with irradiation dose, but the bisphenol based polysulfone maintained its original ductility.

Study of olivine supported copper sorbents performances in the desulfurization process in link with biomass gasification

In this study, a Cu/olivine system was prepared with different loading (3–10wt.%) by wet impregnation method and calcined at different temperatures in order to raise and to optimize its performances in the presence and in the absence of hydrogen in desulfurization process during gasification of biomass. The Cu/olivine catalysts are as well characterized by XRD and H2-TPR experiments. XRD patterns are found to show formation of copper and iron oxides and mixed Cu–Fe oxides after calcination process. H2-TPR results revealed that the materials calcined in the 900–1000 °C temperature range were more difficult to reduce than those calcined at lower temperatures because of their strong interactions between copper and olivine material. Desulfurization over 3% Cu/olivine sorbent calcined in the 900–1000°C temperature range has been considered to be the best materials offering the highest breakthrough times and the highest amounts of H2S removed in the presence or in the absence of hydrogen with low production of SO2. Regeneration/sulfidation cycles performed on 3% Cu/olivine sorbent calcined at 1000°C revealed that the material is not deactivated and exhibits the same performances after 10cycles.

Production of SO<sub>2 </sub>and Lime from Phosphogypsum Reduced with Lignite in a Nitrogen Atmosphere

In this study, using lignite as a reducer, the reaction characteristic of the reduction decomposition of phosphogypsum to SO2 and lime was investigated in a nitrogen atmosphere at different conditions. Scanning electron microscopy and XRD-ray diffraction were used to analyze the solid production. The gas production of SO2 was analyzed by the Gas Analyzers. The experiment results showed that the optimal conditions for production of SO2 are founded to be a molar proportion of C:CaSO4=0.8:1 and a decomposition temperature of over 1000°C.Under these conditions the maximum concentration of SO2 reached to 8.23% (vol. %). The CaO content of solid production increased to 62.57%. The desulfurization rate of phosphogypsum reached to 95.16%.

Implantation of multiply charged sulfur ions in water ice

Sulfuric acid has been suggested to be present on the surface of the jovian moon Europa where it is mixed with the dominant water ice. The formation mechanism of sulfuric acid is still under discussion.We present new experimental results on the implantation of Sq+ (q=7, 9, 11) ions at an energy range between 35 and 176keV in water ice at 80K. Previous results on 200keV S+ implantation in H2O at 80K have also been included in the data analysis. Experiments with multiply-charged ions at different energies are particularly relevant to simulate the complexity of the irradiation environment to which the surface of Europa is exposed being embedded in the jovian magnetosphere.The experiments were performed at the low energy ion beam facility ARIBE of GANIL in Caen (France). 35–176keVSq+ (q=7, 9, 11) ions were implanted in solid H2O layers which were frozen at 80K. Fourier Transform Infrared Spectrometry (FTIR) was used to analyze the sample in the 5000–600cm−1 (2–16.7μm) region with a spectral resolution of 1cm−1.The results of our experiments indicate that implantation produces hydrated sulfuric acid with yields that increase with ion energy, from 0.12moleculesion−1 for 35keV ions to 0.64moleculesion−1 for 200keV ions. We have also searched for the production of SO2 and H2S, but we were not able to find any evidence for their synthesis.We conclude that sulfur ion implantation is the dominant formation mechanism of hydrated sulfuric acid at Europa. The suggestion that the observed distribution of sulfuric acid on the surface is well correlated with the local flux of sulfur ions find a full explanation by present experimental data.

Hydrogen production by flue gas through sulfur–iodine thermochemical process: Economic and energy evaluation

The use of low quality fossil fuel with high sulfur content is becoming more frequent and probably will play a very important role in the future, due to the depletion of reserves.Combustion of this kind of fuels results in the production of SO2 containing flue gas. Obviously, because of its toxicity, and the possibility of deposition in the environment by acid rains, SO2 release into the atmosphere is not permitted, if not within the range of the legal limits. A modified configuration of the Sulfur–Iodine thermochemical cycle could be suitable to treat exhaust flue gases produced by combustion of sulfur-containing fuels. It results in significant cost savings in comparison with conventional sulfur recovery methods. In addition, the production of concentrated sulfuric acid and hydrogen, which are the process outputs, can lead to a significant revenue. In this paper an accurate energy and economic analysis is presented for the modified sulphur–iodine cycle as a sulfur recovery method from SO2 containing flue gases coming from combustion of sulfur-containing fuels. The technical economic feasibility of this new process is compared with existing processes.

Hydrogen production via sulfur-based thermochemical cycles: Part 3: Durability and post-characterization of silicon carbide honeycomb substrates coated with metal oxide-based candidate catalysts for the sulfuric acid decomposition step

This work is a follow-up of previous efforts reported on the synthesis of various single and mixed oxide materials and their evaluation as catalysts for the sulfuric acid dissociation reaction for the production of SO2 and O2. The current work concerns the comparative assessment of Fe2O3, CuO, Cu–Fe, Fe–Cr, Cu–Al and Cu–Fe–Al mixed oxides coated as catalysts on silicon carbide monolithic honeycomb structures, with respect to sulfuric acid decomposition reaction conditions for 100h at 850°C and ambient pressure, as well as their ex-situ characterization after such operation. The exposure conditions are representative to a potential future real application. The exposure time, although of relatively short-term, is adequate to extract safe conclusions on the stability and therefore to a large extent also on the suitability of the candidate oxide-based catalysts. All catalytic systems tested exhibited high SO3 conversions reaching or exceeding 70%, for space velocities in the range of 5–35h−1. For some of the samples, the relatively high initial activity decreased by about 5–10 percentage points in the course of the 100h testing, reaching stable mean values. It was concluded that Fe2O3, CuO and Fe–Cr mixed oxide retained their chemical and structural stability after exposure to reaction conditions, while the other three mixed oxides studied suffered from significant phase decomposition phenomena. Based on the fact that the initial catalytic activity of the Fe–Cr mixed oxide, as identified in a previous comparative study among several materials, was found higher than the ones of Fe2O3 and CuO and relatively close to the one of the highly active but costly Pt/Al2O3 catalyst, the particular mixed oxide is considered a promising catalyst for the SO3 dissociation reaction.

ARCSECOND RESOLUTION MAPPING OF SULFUR DIOXIDE EMISSION IN THE CIRCUMSTELLAR ENVELOPE OF VY CANIS MAJORIS

We report Submillimeter Array observations of SO2 emission in the circumstellar envelope of the red supergiant VY CMa, with an angular resolution of ~1". SO2 emission appears in three distinct outflow regions surrounding the central continuum peak emission that is spatially unresolved. No bipolar structure is noted in the sources. A fourth source of SO2 is identified as a spherical wind centered at the systemic velocity. We estimate the SO2 column density and rotational temperature assuming local thermal equilibrium (LTE) as well as perform non-LTE radiative transfer analysis using RADEX. Column densities of SO2 are found to be ~10^16 cm^-2 in the outflows and in the spherical wind. Comparison with existing maps of the two parent species OH and SO shows the SO2 distribution to be consistent with that of OH. The abundance ratio f_SO2/f_SO is greater than unity for all radii greater than at least 3x10^16 cm. SO2 is distributed in fragmented clumps compared to SO, PN, and SiS molecules. These observations lend support to specific models of circumstellar chemistry that predict f_SO2/f_SO>1 and may suggest the role of localized effects such as shocks in the production of SO2 in the circumstellar envelope.

The direct oxidation of hydrogen sulphide over activated carbons prepared from lignite coal and biochar

AbstractPhysically (steam) and chemically (KOH) activated carbons prepared from Luscar coal and biochar were used for removal of low concentrations of hydrogen sulphide (1 mol%) in methane. A modification method including acid treatment and thermal desorption in an inert atmosphere was used and the effects of this modification on the porous structure, surface chemistry, and ash content were studied. It increased total pore volume of activated carbons prepared from coal and biochar by 43% and 11%, respectively. Acid treatment changed the surface chemistry of activated carbons. Also, thermal desorption removed most of the acidic groups, especially carboxylic groups. The break‐through times corresponding to 80% removal of H2S using modified activated carbons prepared from coal and biochar were increased to 102 and 131 min, respectively. Also, the production of SO2 as an undesirable by‐product was less than 1.9% of H2S fed into the reactor.

Transient infrared spectra of CH3SOO and CH3SO observed with a step-scan Fourier-transform spectrometer

A step-scan Fourier-transform spectrometer coupled with a multipass absorption cell was employed to monitor time-resolved infrared absorption of transient species produced upon irradiation at 248 nm of a flowing mixture of CH(3)SSCH(3) and O(2) at 260 K. Two transient bands observed with origins at 1397±1 and 1110±3 cm(-1) are tentatively assigned to the antisymmetric CH(3)-deformation and O-O stretching modes of syn-CH(3)SOO, respectively; the observed band contour indicates that the less stable anti-CH(3)SOO conformer likely contributes to these absorption bands. A band with an origin at 1071±1 cm(-1), observed at a slightly later period, is assigned to the S=O stretching mode of CH(3)SO, likely produced via secondary reactions of CH(3)SOO. These bands fit satisfactorily with vibrational wavenumbers and rotational contours simulated based on rotational parameters of syn-CH(3)SOO, anti-CH(3)SOO, and CH(3)SO predicted with density-functional theories B3LYP/aug-cc-pVTZ and B3P86/aug-cc-pVTZ. Two additional bands near 1170 and 1120 cm(-1) observed at a later period are tentatively assigned to CH(3)S(O)OSCH(3) and CH(3)S(O)S(O)CH(3), respectively; both species are likely produced from self-reaction of CH(3)SOO. The production of SO(2) via secondary reactions was also observed and possible reaction mechanism is discussed.

Direct oxidation of hydrogen sulphide to sulphur using impregnated activated carbon catalysts

AbstractLow concentrations of H2S were directly oxidized to sulphur and small quantities of SO2, over seven different activated carbons with or without impregnation. The effectiveness of virgin activated carbon was tested at 175°C, 700 kPa, and O2/H2S ratio with 5% greater than stoichiometry. The conversion of H2S was 99.9 mol% with SO2 production of 3–6%, for 360 min runtime for Fisher coconut shell activated carbon and 648 min for Envirotrol bituminous (EB) activated carbon. Then the activated carbons became deactivated due to deposition of sulphur on the surface. Under these conditions mesoporous activated carbons such as EB and Hydrodarco had the longest breakthrough time. The addition of 5.5 wt% ammonium iodide, potassium iodide and potassium carbonate individually to EB decreased the production of SO2 while having minimal effect on the overall H2S conversion. The addition of 5.5 wt% NH4I decreased the average SO2 production from 2.5% to 0.9%. The activation energy for the H2S oxidation on the 5.5 wt% NH4I on EB activated carbon was determined to be 40 kJ/mol.